Hypercalcemia is a severe complication of malignant disease. The agents responsible for the hypercalcemia are not well characterized, though some of them seem to act by stimulating osteoclastic bone resorption. The study of these factors has been hampered by the small amounts of material available from tumors removed at surgery and the difficulty of establishing human tumors in culture. In this grant proposal, we will assess the significance of the bone-resorbing factors we have found in the urine of patients with malignancy-related hypercalcemia. Bone-resorbing activity will be purified by conventional-\and high-performance liquid chromatography. We also will examine the urine for the presence of other biological activities such as adenylate cyclase-stimulating and transforming growth factor activities which have been implicated as potential mediators of malignancy-associated hypercalcemia. When possible, we will examine tumor tissue extracts and conditioned medium from tumor cells from the same patient to establish whether any bone-resorbing activity found in the urine is similar or identical to that found in tumor extracts or conditioned media. If these studies are successful, it will establish the use of urine as a convenient and plentiful source of materials for studying some of the mediators of malignancy-associated hypercalcemia. The study of multiple biological activities in parallel also will help to determine the relationship of such activities to hypercalcemia. (J)